\begin{Bmatrix} B_{0}(z)=1\\ B_{1}(z)=z-1\\ B_{2}(z)=2z^2-3z+1\\ etc.\\ \end{Bmatrix} andgenerally [math]B_{k}(z)=\sum_{h=0}^{k}b_{k, h}z^{k}[/math]
